What is a Supplemental Type Certificate? How are STCs obtained?

A supplemental type certificate (STC) is a type certificate (TC) issued when an applicant has received FAA approval to modify an aircraft from its original design.  The STC, which incorporates by reference the related TC, approves not only the modification but also how that modification affects the original design.

Original Design Approval Process

An original FAA design approval is a five-phase process in which an applicant applies for, and the FAA may issue, a type certificate or design approval of a product or a major design change to a product. A product is an aircraft, an aircraft engine or, an aircraft propeller. The process, if approved, results in the issue of a type certificate, a supplemental type certificate or an amendment to either a type certificate or supplemental type certificate as contained in 14 CFR part 21.

The principles of up-front planning, project management, and documenting the certification process are applicable to all applicants. A major change to the design of a type-certificated product is approved by a separate process and issued on a supplemental type certificate or an amended type certificate.

These are common inquiries. They are usually followed by "How much does an STC cost?" Once you know the answers to the first two questions, we think you will agree that, for the professional aircraft operator owner or pilot, an STC is a wise long-term investment rather than an expense.


Original aircraft manufactures obtain a Type Certificate (TC) from the FAA in order to go into production. Any company that produces a product to modify aircraft must obtain a Supplemental Type Certificate from the FAA. There are many steps involved in the STC approval process. They include extensive technical analysis and thorough regulatory review. Substantial time is devoted to engineering, testing and in some cases actual flight. After all the required submissions have been made, the FAA must verify these data. Only then does it issue an STC, which is an authorization to accomplish the modification on one or more aircraft.  The FAA’s permission to manufacture components or modification kits is called a Parts Manufacturing Authority (PMA).

A recently issued STC was found to require 2,500 pages of written material, drawings and test reports. These include:


Certification Report

Stress Analysis

Electrical Load Analyses

System Safety Analysis

Airplane Flight Manual Supplement

Instructions for Continued Airworthiness

Human Factors Analysis


The aircraft modification must prove acceptable under every conceivable condition. Once completed, this process ensures both performance and safety.

In addition to certifying that the modification will be performed to government standards, the STC could not be granted until a modified aircraft was completely flight tested by an FAA pilot (or FAA Designee). This was done in accordance with a detailed and exhaustive test plan.

 The test aircraft was outfitted with laboratory-grade instruments to demonstrate compliance with a detailed checklist of mandatory criteria.

 The program described above took two years to complete and cost more than $1 million. When pro-rated over the number of aircraft covered by this STC, the fee charged buyers, for certification alone, was only $10,000 per installation. The true value of an STC is realized through the improved performance and greater utility of the airplane.

 The aircraft modifications have been installed on planes that currently operate in countries all over the world. Many of the same personnel that developed this STC now provide Jetaire with the same dedication, service and expertise that have made it one of the most beneficial upgrades available for commercial aircraft.